w*****m
发帖数: 20421 | 1 300 mrem a year is ok
I smoke 1/2 pack of cigarettes every day of the year (18 mrem)
X-Ray - Chest 10 mrem
CT Scans - Head 200 mrem
I live in a state that borders the Gulf or Atlantic coasts (16 mrem)
I live in the Colorado Plateau area (63 mrem)
I live elsewhere in the continental U.S. (30 mrem)
I live in a stone, adobe, brick, or concrete building (7 mrem) |
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w*****m
发帖数: 20421 | 2 你自己看看辐射剂量有多少，对比一下，一年不超过几百，问题不大
牙医的XRAY，就是天天照也不及一次CT SCAN头部的，照CT的也没
几个得脑癌的，这个典型的杞人忧天
X-Ray - Chest 10 mrem
X-Ray - Dental Bitewing/Image 0.5
CT Scans - Head 200
CT Scans - Chest 700
I live in the Colorado Plateau area (63 mrem)
I live elsewhere in the continental U.S. (30 mrem)
I live in a state that borders the Gulf or Atlantic coasts (16 mrem)
I live in a stone, adobe, brick, or concrete building (7 mrem) |
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h*******6
发帖数: 3228 | 3 【 以下文字转载自 Seattle 讨论区 】
发信人: onetiemyshoe (onetiemyshoe), 信区: Seattle
标 题: 核辐射检测数据. Updated daily.
发信站: BBS 未名空间站 (Mon Mar 14 10:59:06 2011, 美东)
So far, 3/14/2011 & 3/15/2011, in Seattle, only background radiation = 0.008
mrem/hour. 谢谢大家给发包子 :-)
3/16/2011, radiation around .011 mrem/hour. This is NOT significant. Please don't panick.
3/17/2011, radiation around .010 mrem/hour. This is NOT significant.
3/18/2011, radiation around .010 mrem/hour. Good news from Japan: the cooling system rest... 阅读全帖 |
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w******y
发帖数: 8040 | 4 同学， 你做的这个research很好， 不过你的理解是有缺陷的.
首先回答你做X-ray or CT scan的问题， 这是不包含在我们讨论的100 mREM里的，全
部引文是：
"The ICRP recommends limiting artificial irradiation of the public to an
average of 100 mrem (1 mSv) of effective dose per year, not including
medical and occupational exposures. "
所以你不要试图把medical exposure加进来 混淆视听， 也就是说图中manmade 310
mREM根本不在讨论中， 这个artificial是beyond 图中manmade部分的。
CT 剂量和次数都严格受法规调控。这正是问题所在， 政府明确调控和规定了
diagnostic procedure的潜在危害和安全剂量， 公众也都知情； 这个Half moon bay
正好相反， 高于正常背景辐射5倍， 公众既不知情，也没有任何noti... 阅读全帖 |
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z**n
发帖数: 22303 | 5 先剽窃一个：
From onetiemyshoe：
西雅图
3/14/2011 & 3/15/2011, 0.008 mrem/hour.
3/16/2011, 0.011 mrem/hour.
3/17/2011, 0.010 mrem/hour. |
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r**e
发帖数: 2504 | 6 seattle版有人每天用检测器测的。
昨天 0.008 mrem/hour
今天 0.011 mrem/hour
明天? |
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w****a
发帖数: 2049 | 7 around 0.5 mrem per hour of jet flying, which equals to one dental x ray (
intro dental x ray, ie. bitewing). our one day background radiation is
around 1 mrem.
emf radiation is another thing. it is similar to what you get from MRI, not
x ray. EPA guideline is less than 1 milligauss for long term living
environment. However, till now, no one can say conclusively that living in
high emf env. can cause harm to human. |
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h********o
发帖数: 3320 | 8 你这是说的Ionizing radiation，高压线辐射属于non-ionizing radiation，有多少危
害没有定论。
300 mrem a year是指的美国人平均一年接受的天然ionizing radiation辐射剂量。对
于职业人员，一年接受的辐射剂量上限是50 mSv，大约是5000 mrem。 |
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m***n
发帖数: 690 | 9 湾区没有人帮助测测的？哪位大侠有geiger counter啊？
【 以下文字转载自 Seattle 讨论区 】
发信人: onetiemyshoe (onetiemyshoe), 信区: Seattle
标 题: 核辐射检测数据. Updated daily.
发信站: BBS 未名空间站 (Mon Mar 14 10:59:06 2011, 美东)
So far, 3/14/2011 & 3/15/2011, in Seattle, only background radiation = 0.008
mrem/hour. 谢谢大家给发包子 :-)
3/16/2011, radiation around .011 mrem/hour. This is NOT significant. Please
don't panick.
Radiation is measured using a geiger counter, it probably costed around $400
(worth the peace of mind); On the other hand, the... 阅读全帖 |
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c*****a
发帖数: 1238 | 10 Thanks for info.
3/16/2011, radiation around .011 mrem/hour.
which is equal to 964 mrem/year, or 9.64 mSv/year.
seems elevated, keep watching. |
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w******n
发帖数: 352 | 11 http://www.ors.gatech.edu/rsm.pdf
7.2
Embryo/Fetus Dose Limits
7.2.1
Female radiation workers who become pregnant and declare the pregnancy in
writing to the RSO shall be limited to a dose of 500 mrem for the
gestational period of the fetus.
7.2.2
The female worker who chooses to declare her pregnancy should inform her
supervisor (AU) and the RSO. Appropriate steps to limit exposures and to
ensure that exposure of the embryo/fetus shall not exceed 500 mrem per
gestation period will be determined |
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i******s
发帖数: 8734 | 12 靠.
这不就是本底吗?
btw: 作这种测量的时候, 一般不用mrem 作单位.
用R/h作单位
俺现在边上就有detector ,
测到的结果是 0.008~0.011 mR/H之间 变化
知道不知道运送放射源的要求是啥不?
说出来是不是要把你吓死?
满足这个要求, 就能直接用fedex 运. 和你shipping 一般的东西没区别. |
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w*****m
发帖数: 20421 | 14 CT SCAN头部 200比你那个0.5牙齿，有可比行么，其实我觉得一个人一年接受几千MREM
问题都不大，只要不是每年都好几千就没事 |
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d******n
发帖数: 509 | 15 昨天我是才查了这个。 我是做实验要用到 125 I. 每次试验用量是 1-2 micro-curie
. 我看了一下， 孕妇的上限是 500 mrem, 就是相当于 0.5 micro-curie， 还没有搞
明白 这个上限是用量，还是吸收量。 好担心。
准备第一次看 ob后,立刻给老板和 radiation safety office 说我怀孕了. |
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c****d
发帖数: 3097 | 16 单位换算：
1000 μSv = 1 mSv = 0.1 rem = 100 mrem |
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o**********e
发帖数: 18403 | 17 3/14/2011 Seattle, only background radiation = 0.008 mrem/hour.
请西海岸和夏唯一的同学帮着测量一下. 数据请进回贴, 请看官多发包子 :-) |
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b*******r
发帖数: 6655 | 18 it is a significant level, triggering the withdraw of emergency personnel
To put it in perspective, the last time I was in the vault, I only picked
up about 50 mrem in 2 hours. |
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g**t
发帖数: 1872 | 19 你作的是shielding，跟natural background不一样哦。一个人平均大概应该就是1
mrem per day，那个除24小时，应该
就是四十多个urem。 |
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w******y
发帖数: 8040 | 21 The International Commission on Radiological Protection (ICRP) recommends
limiting artificial irradiation of the public to an average of 100 mrem (1
mSv) of effective dose per year
自己算half moon bay对应的dose吧 |
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w******y
发帖数: 8040 | 22 小同学, 你能就别人的提问正面回答问题吗?
你口口声声说这个网站是专业人士网站
我随随便便一翻就找出来,
该网站自己列出的文献, 根本不支持该网站claim的东西
完全是个无效引用,
这像是一个严谨的专业人士的样子吗?
而且该网站关于granite CPM的逻辑, 您一直躲着不敢回应,
又说明了什么?
您到底有什么证据支持这个网站的权威性? 愿意洗耳恭听
至于100 mREM超标的辩论, 我一开始就强调不是我主要的point
你偏偏只对这个不是主要point的次要point有讨论的兴趣和勇气
那也可以,
不过你在辩论过程中, 不断变换论点, 一会儿说上限的定义不对,
一会儿把medical exposure拉进来凑数,
随着我一一用文献指出你说的都是不对的,
你最后又转进到去海滩时间的问题上了....
那么我问你, 如果有一群闲人天天泡这个海滩, 对它们来说是不是超标?
它们该不该有知情权?
那个政府官员和我用的是同样的外推逻辑, 它的5万小时是不是故意误导?
radiation
below
on |
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b*********d
发帖数: 3539 | 23 The exact units of measurement vary, but light radiation sickness begins at
about 50–100 rad (0.5–1 gray (Gy), 0.5–1 Sv, 50–100 rem, 50,000–100,000
mrem).
750 rad = 7.5 Gy = 7.5 sV = 7500 msV
4500-5000 msV: LD50 in humans (from radiation poisoning), with medical
treatment，
如果750 rad数字没错的话，加州也就死一半吧，剩下一半，身体好的，得扑腾大半年
之后才得癌症。
http://en.wikipedia.org/wiki/Orders_of_magnitude_%28radiation%2 |
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o**********e
发帖数: 18403 | 24 So far, 3/14/2011 Seattle, only background radiation = 0.008 mrem/hour. 谢谢大
家给发包
子, I'll need a lot of it since i am expecting :-)
Radiation is measured using a geiger counter, it probably costed around $400
(worth the peace of mind); On the other hand, the leaks in Japan is not
likely to cause a lot of radioactive fallout here (my guess). People in UW
may be able to loan one out from the
physics department.
this link has information about average background radiation.
http://www.physics.is... 阅读全帖 |
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c*****a
发帖数: 1238 | 25 The average annual dose in the Northern Hemisphere is less than 1 millirem
annually. That falls below the 100 millirem exposure limit the Nuclear
Regulatory Commission recommends.
so 0.008 mrem/hour.
is close to 70 millirem per year...
where is your location of data reporting? |
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c*****a
发帖数: 1238 | 27 sorry, should be 96.4 mrem/year, or 1 mSv/year.
I should double check, as I was hurry for a meeting.
Thanks for a few people indicate the error. |
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o**********e
发帖数: 18403 | 28 Update on Iodide in Milk/Water: Radioactive iodide has half life of 8 days,
and the concentration is very low, so my geiger counter can't detect a
significant difference. Unless, I take it to the lake daily, which is a lot
of trouble. Alternatively, I'll just drink water and test my thyroid
everyday. I don't drink milk. I don't expect the numbers to spike up. If it does, I'll need to move somewhere else or drink only bottled water or water stored for 2+ weeks...
So far, 4/3/2011, in Sea... 阅读全帖 |
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l****e
发帖数: 137 | 29 This data is old. Current limit in shielding design is 0.25 mrem/hr or 2.5
uSv/hr, ~10 times lower.
Also 辐射服 can only stop alpha, beta and may be very low energy gamma decay
. its purpose is mainly to stop
radiation contamination. It is useless at a reactor site when the main
contributions are from neutrons and
gammas. Intake of 300 rem or 3 Sv could cause the body to fail within a
week or two. At Chernobyle ~60 of
2000 died due to such a dosage, though i have not confirmed on this data. |
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l****e
发帖数: 137 | 30 Your standard is probably for radiation worker, mine is for general public,
though it may be conservative.
NCRP's standard always falls behind ICRP, that could be another underlying
reason.
To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
and energy, if in your case just
for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
it is designed to stop high energy
gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
it with ~ 7 cm Pb. |
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